Traffic signal



March 16, 1937. c ADLER' JR 2,074,246

TRAFFIC S IGNAL Filed 001:. 17, 1936 Patented Mar; 16,- 1937' UNITEDSTATES PATENT OFFICE TRAFFIC SIGNAL Charles Adler, Jr., Baltimore, Md.Application October 17, 1936, Serial No. 106,247

3 Claims. .(01. 117-329) means must be provided to overcome this hazard.

to be observed by an ofiicer and the signal restored 15 to normal.

, In accordance with the invention, a diffusing lens and a reflector incombination witha lamp having main and secondary filaments is employed,the filaments being longitudinally spaced and the filament adjacent thelens having a considerably longer life and lower Wattage than the mainfilament. The main filament is disposed in focus with the reflector sothat substantially parallel reflected rays are utilized to present a 25normal full illumination of the signal area. The secondary filament isarranged out of focus with the reflector and relatively, closer to thecover glass, whereby, when the main filament burns out, the direct raysform the low wattage longer 30 life secondary filament in combinationwith the diffusing lens, illuminates the signal in the form of adefinite illuminated spot visibly of less area than the signal area.Thus, the signal remains operative, but an officer, and others may ob-35 serve that the signal is not functioning normally and make report tothe proper authority.

Referring to the drawing: Figure 1 is a top view partly in section ofone form of the invention; 40 Figure 2 is a similar view of amodification in which a diffusing means is formed on the bulb; Figure 3is an elevation of the cover glass or lens when the main filament burnsout showing the definite illuminated spot provided by the sec- 45 ondaryfilament and diffusing lens, and

Figure 4 is a similar view with a lens of modified structure. I

Referring to Figure 1, I have shown a diffusing lens or cover glassconstituting the signal area 50 at Ill, such lens consisting of amultiplicity of prisms on its interior surface which may take variousforms. The reflector is indicated at H and is preferably of theparabolic type as shown. The cover glass or lens and the reflector form5 a signal housing within which is positioned the illuminating meanscomprising the incandescent lamp l2 of the gas filled or evacuated type.This lamp includes a bulb I4 of clear glass, one end of which is sealedinto a screw threaded base I5, and has the usual stem l6, and pillar H.The 5 main filament carried by the pillar is indicated at I8, and forpurposes of illustration will have,- for example, a life of .about 1500hours and a wattage, for example, of about 25 watts to 50 watts. Thesecondary filament I9 is disposed in 10 longitudinal alignment on thepillar with but in spaced relation to the mainv filament as shown, andwill have for purposes of illustration a life of about 3,000 hours and awattage of substantially 7% watts to 10 watts.

The spacing of the filaments is important for several reasons. Referringto Figure 1, the main filament is so disposed as to be in focus with thereflector whereby the parallel reflected rays are utilized to present anormal full illumination of the signal area or diffusing lens. Further,the secondary filament .is so disposed as to be out of focus with thereflector and being relatively closer to the diffusing lens, when themain filament burns out, the direct rays from the low wattage longerlife filament in cooperation with the diffusing lens, illuminates thesignal in the form of a definite illuminated spot visibly of less areathan the signal area as shown in Figures 3 and 4.

The distance of spacing of the filaments on the pillar in longitudinallyspaced relation, moreover, is such that when one filament, for examplethe main filament burns out, there is no danger of arcing such as woulddestroy the remaining filament. a

The filaments are permanently and completely electrically connected inparallel, preferably as shown at 20 through the main lead wires 2| and22 within the lamp and the base has the usual electrical connection witha lamp socket, e. g. the lead wire 2| terminates at the insulated bottomof the base and the lead wire. 22 terminates at the threaded ferrulesurrounding the base. The filaments are preferably circular as shown,but similar elongated filaments of other types may be foundsatisfactory.

Referring to Figure 2, the lamp has a frosted 'or transluscent tip orend 25 of an area to diffuse the direct rays from the secondary filamentin order to produce an illuminated spot as shown in Figures 3 and 4.This lamp may be used with a diffusing lens but is particularly usefulwhere the cover glass has little light diffusing properties or isentirely devoid of the same.

The lens illustrated in Figure 4 is in accordance with my Design Patent92,055, April 24, 1934, and the prisms are indicated at 23 andcorrugated areas at 24.

As will be observed, when the signal is in operation, both filaments areenergized and incandescent, and the signal area is fully illuminated bythe main filament to give the required signal. When this main filamentburns out, the longer life low wattage filament remains illuminated andproduces in cooperation with the difiusing means, namely the lens, thefrosted area, or both, a definite illuminated spot as shown in Figures 3and 4. This spot being smaller in area than the total normal illuminatedarea of the signalis quite definite and visible to an officer,maintenance force or the public so that the failure of the main filamentwill be observed and the signal restored to normal. The invention issimple, thoroughly reliable, as will be appreciated, and will serve tocurtail substantially accidents due to the burning out of the electriclights in the signal system.

I claim:

1. A signal comprising a reflector and a light diffusing cover glass,illuminating means positioned between the cover glass andsaid reflector,said illuminating means comprising electrical light sources arranged inlongitudinal relation and connected in parallel, one of said lightsources disposed in the focal plane of the reflector for causingsubstantially parallel reflected rays to illuminate the signal area andanother having a longer life disposed out of the focal plane of thereflector.

2. A signal comprising a reflector and a diffusing cover glass,illuminating means positioned 1 between the cover glass and saidreflector, said illuminating means comprising electrical light sourcesarranged in longitudinal relation and connected in parallel, one of saidlight sources having a high wattage and disposed in the focal plane ofthe reflector and another thereof having a lower wattage but a longerlife and disposed out of the focal plane of the reflector.

3. A' signal comprising a reflector and a light diffusing cover glass,illuminating means positioned between the cover glass and saidreflector, said illuminating means comprising electrical light sourcesarranged in longitudinal relation and connected in parallel, one of saidlight sources disposed in the focal plane of the reflector for causingsubstantially parallel reflected rays to illuminate the signal area andanother having a longer life disposed out of the focal plane of thereflector, said diflusing cover glass and reflector in cooperation withsaid light source having the longer life producing on said diffusinglens when the other light source fails, a definite indication of suchfailure.

CHARLES ADLER, JR.

